Electroresponsive apparatus



May 17. 1927. 1,629,011

H. A. THOMPSON ELECTRORESPONSIVE APPARATUS Filed April 7. 1923,

S: INVENTQR:

BYQI' 'N-w ATTORNEY- Patented May 17, 1927.

HOWARD A. THOMPSON, OF WILKINSBURG,

PATENT OFFICE.

PENNSYLVANIA, ASSIGNOR TO THE UNION SWITCH & SIGNAL COMPANY, OFSWISSVALE, PENNSYLVANIA, A CORPORATION 01' PENNSYLVANIA.

ELECTRORESPONSIVE APPARATUS.

Application filed April 7,

My invention relates to electro-responsive apparatus, and particularlyto apparatus adapted for intermittent operation. Apparatus embodying myinvention is particularly well suited for, thou h in no way limited to,the operation of Trighway crossing signals of the wi -wag type.

I Wlll describe a ew forms of apparatus embodying my invention, and willthen point out the novel features thereof in claims.

In the accompanying drawing Fig. 1 is a diagrammatic vlew showing oneform of apparatus embodying my invention. F i s. 2 and 3 are viewsshowing modifications o the apparatus shown in Fig. 1 and also embodyingmy invention.

Referring first to Fig. 1, the reference characters 1 and 1" designatethe track rails of a railway over which traflic normally moves in thedirection of the arrow, and which railway is intersected by a highwayExtending to the left from the highway U is a track section AB which isseparated from the remainder of the track by insulated joints 2. Thissection is provided with a track relay It connected across the railsadjacent the intersection of highway C and the section A'--B. Thissection is also provided with a source of track circuit currentcomprising, as shown in the drawing, a secondary windin 31 of atransformer T, whose primary 32 1s constantl supplied with alternatingcurrent from line'wlres 3 fed by a generator M. The signal is mounted insome exposed place near the grade crossing and comprises a banner Hhaving an arm 26 pivotally mounted at point 33 and carrying aconspicuous emblem such as a disk 27 bearing a warning such as thelegend Stop. The arn'lature 29 of a tractive magnet G is mechanicallyconnected to the banner H in such a manner that when magnet G isenergized, armature 29 is drawn upwards and banner H is swung to theright and is restrained in such a position that disk 27 is concealed bya shield 30. Interposed between armature 29 and banner H is a resilientmember, preferably in the form of a coil spring 28. The

magnet G is provided with a circuit which passes from a source of energyas a second 1923. Serial No. 630,510.

ary 5 of transformer D through wire 18, front contact 6? of relay R,wire 17, winding 16 of magnet G, wires 15, 13, and 12, back to secondary5 of transformer D. This circuit is closed only when relay R isenergized, in which case banner H is concealed 11011! view. The primary4 of transformer D is constantly supplied with alternating current fromline wires 3.

When section A-B is occupied by a train, relay R is de energized thusopemng front contact 6--7 and de-energizing magnet G. At the same timebanner H is caused to oscillate by the apparatus which I will nowdescribe.

The reference character F designates an electro-magnetic devicecomprising a core F provided with a winding 20, two legs F and anarmature F which armature is located between the legs F and in operativerelation with res ect to the core F This armature F is biased by somemeans such as gravity to a position wherein it is spaced from the core FWhen winding 20 is energized, armature F is picked up or drawn towardthe core F thus completing the magnetic circuit. Spacing pins 21. may beinserted in the face of core 21 to prevent the actual contact ofarmature F and core F, thus eliminating the possibility of sticking ofthe armature due to residual magnetism.

The armature F is mechanically connected to the banner H by means of abell crank 22 pivoted at point 23 and so disposed that alternate raisingand lowering of this armature will produce oscillations in the bannerabout its pivot 33. A resilient spring 25 is inserted between the bellcrank 24 and armature F. Since the reluctance of the magnetic circuit ofdevice F is considerably less when the armature F is in its upperposition than when in its lower position, it follows that the reactanceof the coil 20 is considerably greater when armature F is in its upperposition than when in its lower position. The energization of coil 20 iscontrolled by means of a thermo-sensitive cell E having a heatingelement 9 and an element 10 of thermo-sensitive material, that is,material which has the property of varying its electricalcharacteristics in response to is as follows:

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changes in temperature. These two elements are in mutual electricalcontact and are so associated that the thermo-sensitive element 10 issubjected to variations in temperature of the heating element due to thepresence and absence of current in this heating ele ment. This cell iiis provided with a heating circuit which peer. from secondary oftransformer B through wire 18, back contact S of relay R, heatingelement 9, non inductive resistance 11, and wire 12 back to secondary 5of transformer D.

This circuit is closed only when relay '1 is ale-energized. Thetliermo-sensitive cell E is provided with another circuit which passestrom secondary 5 0t transformer I), through wire 18, contact of relay R,heating element 9 and thermo-sensitive element 10 0t theiano-sensitivecell E, wire it), winding 0t device F, and wires ll, 1-3 and 1'2 bacl:to secondary 5 of transformer i). This circuit is closed only when relayit is tie-energized.

Assuming that relay it is open, so that the banner H is released, theoperation of device As soon the circuit for heating element 5) ofthermo-sensitive cell E is closed at contact (3-43, current flowsthrough this element thus generating heat which is transmitted tothermo-sensitive clcmeat 10. The consequent increase in the temperatureof this thermosensitive element decreases its resistance and allows asmall amount of current to tlow through it. This current is notsuliicient to picl; up the armature F but it is sutiicient to furtherincrease the temperature of element it) with a resulting furtherdecrease in the resistance of this element. This action accumulative andcontinues until the current through thermosensitive element it) andwinding 20 is enough to picl: up armature F, thus swinging banner to theleft. Now when the armature l moves to its upper position, therinictance of the winding 20, and hence the total impedance oi thecircuit o'l" which the winding 20 a part, is considerably increased. Theresulting decrease in the current through the thermo-sensitive elen'ientl0 de' reases the temperature of this element which increases itsresistance and further reduces the current through the element. Thisaction is also accumulative and continues till the current is reduced tosuch a low value that it is no longer suiiicient to hold arnniture F inits upper position. The armature thereupon returns to its lowerposition. This cycle is repeated as long as relay R tie-energized.

The voltage available for operating derice. F may be varied by variationin the value of resistance ll which connected in series with heatingelement 9 ol thermosensitive cell. E and in parallel with winding- 20 ofdevice F. The time interval between successive movements of armature Fmay be regulated by proper design and proportioning of device F andthermo-sensit-ive cell E.

The operation of the entire apparatus is as follows:

ilhen section A-B is unoccupied, relay It is energized. and magnet. G,also being energized, holds banner H behind the shield 30. N ow it atrain enters section A-B, relay R becomes tie-energized, and this inturn deenergizes magnet it so that armature releases the banner ll. Theopening olY relay It also energizes thermo-sensitivc cell E which thencauses armature F of device F to move up and down thus causing banner Hto oscillate or wag back and forth on its axis 3?) as hcreinbcioreexplained. This action continues until the train leaves the section je-Bwhereupon relay R will he energized, and the consetuient. energizationot magnet G restores the ajnaaratus to normal.

lfteterring now to Figs. 2 and 3, the change in the total impedance ofthe circuit which includes winding 20 of device 1* resulting from thechange in the reactance of winding it) due to the picli up of arnuiture29 may he aceentuatiwl by introducing a capacity in this circuit. inorder to obtain a large capacity from a comjlenscr of reasonable size astep-up transformer S may be used to increase the voltage available atthe terminals of the comlenser d. The transformer may be connected inparallel with winding 20 as shown in Fig. 2, or in series with winding20 as shown in Fig. 3. \Vith the parallel connection shown in Fig. 2,the condenser is in resonance with winding 20 when plunger F is closedagainst core 1*, whereas with the series connection shown in Fig. 3 thecorn denser is in resonance with winding 20 when the plunger F hasdropped away from the. core.

Although I have herein shown and de scribed only a few forms ofapparatus embodying my invention it is understood that, various changesand modifications may be made therein within the scope of the appendedclaims, without departing from the spirit and scope of my invention.

Having: thus described my invcnliomwhat I claim is:

1'. In combination, an electric conductor. a device controlled by theflow of current in said conductor and operating when such currentexceeds a given value to increase the impedance of said conductorthereby decreasing the value of the current, and means included incircuit with said conductor and responsive to a decrease in said currentfor further decreasingthis current to a value below said given value.

2. In combination, a magnet winding, a device controlled by said magnetwinding and operating when the flow of current in Ill) lll

said winding exceeds a given value to increase the reactance of saidwinding thereby decreasin the value of the current, and means incluc edin circuit with said conductor and responsive to a decrease in saidcurrent for further decreasing this current to a value below said givenvalue.

3. In combination, a magnet having a core provided with a winding havingan electric current flowing attimes therein, an armature controlled bysaid magnet and operating when said current exceeds a given value todecrease the reluctance of said core thus iucreasiln the reactance ofsaid winding and thereby decreasing the value of the current, and meansincluded in circuit with said conductor and responsive to a decrease insaid current for further decreasing this current to a value below saidgiven value.

4. In combination, an electric conductor, a device controlled by theflow of current in said conductor and operating when such currentexceeds a given value to increase the impedance of said conductorthereby decreasing the value of the current, means for accentuatin suchimpedance change, an element included in circuit with said conductorhaving a high negative temperature coefiicient, and means for varyingthe temperature of said element.

5. In combination, an electric conductor, a device controlled by theflow of current in said. conductor and operating when such currentexceeds a given value to increase the impedance of said conductorthereby decreasing the value of the current, acapacity connected inparallel with said device, an element included in circuit with saidconductor having a high negative temperature c0- eflicient, and meansfor varying the temperature of said element.

In testimony whereof I afiix my signature.

HOWVARD A. THOMPSON.

